Pivoted tooth-holder for tunneling machine



April 22, 1969 G. A. PETERSEN 3 PIVOTED TOOTH-HOLDER FOR TUNNELING MACHINE Filed Jan. 9, 1967 Sheet I of 2 5 \j s E 3 FIG. 2. 2 :1 INVENTOIL k GERALD A. PETERSEN PATENT ATTORNEY A ril 22, 1969 G. A. PETERSEN 3,439,758

PIVOTED TOOTH-HOLDER FOR TUNNELING MACHINE Filed Jan. 9, 1967 Sheet 2 of 2 4 F .2340 4 t I l I l 23b1 I INVENTOR. GERALD A. PETERSEN PATENT ATTORNEY FIG. 4.

United States Patent 3,439,758 PIVOTED TOOTH-HOLDER FOR TUNNELING MACHINE Gerald A. Petersen, Cupertino, Calif. Petersen Engineering Co. Inc., 950 Kifer Road, Sunnyvale, Calif. 94086) Filed Jan. 9, 1967, Ser. No. 608,231 Int. Cl. E2lc 13/12; E211) 9/26; E21d 9/00 US. Cl. 175381 Claims ABSTRACT OF THE DISCLOSURE It has been found desirable to reverse the direction of rotation of tunnel machine cutter wheels from time to time in order to compensate for the tendency of such wheels to drift out of straight line due to the reaction to the rotation thereof. The present invention provides pluralities of pairs of tooth holders, each having a replacable tooth and each of which is movable between an operative and inoperative position, so that one tooth of each pair is operative during rotation in one direction and the other in the opposite direction. Means is provided for automatically reversing the positions of the holders between operative and inoperative positions, depending upon the direction of rotation. A preferred means comprises a resilient member which is dragged across the tunnel face when the tooth with which it is associated is in inoperative position, and which upon reversal of direction of rotation of the wheel engages the tunnel face and retards rotation of its holder relative to the wheel, thereby causing the holder to pivot into operative position.

A principal feature and advantage of the present invention is the provision of means for automatically shifting the teeth and their holders between operative and in operative positions upon reversal of direction of rotation of the tunnel machine cutter wheel. This feature of the invention eliminates the necessity of manually resetting the teeth when the direction of rotation is changed.

A further feature of the invention is the provision of means for holding the teeth so that when they are in operative position they are held at the most effective angle relative to the tunnel face for digging action. When the teeth are in inoperative position they are disposed relative to the tunnel face so that they they create no interference with rotation, nor is their cutting edge worn.

Another advantage of the invention is the facility with which the teeth may be replaced when worn.

A still further feature of the invention is the facility with which the holders themselves may be replaced when required.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

FIG. 1 is a fragmentary front elevational view, somewhat schematic in form, of a portion of a cutter wheel for a tunneling machine.

FIG. 2 is an enlarged fragmentary sectional view taken substantially along the line 22 of FIG. 1.

FIG. 3 is a fragmentary plan view of a portion of the structure of FIG. 2.

FIG. 4 is a transverse sectional view taken substantially along the line 4-4 of FIG. 3.

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FIG. 1 illustrates a portion of a reversible cutter wheel 11 for a tunneling machine. A central member 12 is provided connected by means not herein illustrated or described to a reversible drive means for rotation of wheel 11 in either direction. In the position of the wheel illustration in FIG. 1, the Wheel is advancing toward the viewer and teeth are in operative position for rotation counter-clockwise. It will be understood that wheel 11 may be of large size, such as 25 feet in diameter, and is used for tunneling through dirt and soft rock. It has been found from experience that if the wheel 11 is turned continuously in a single direction, the hole which is bored will tend to drift from a straight line, whereas if the direction of rotation is reversed at approximately equal time intervals, the deviation from a straight line in each direction of rotation will tend to be compensated and for practical purposes the tunnel is bored in a straight line. The machine is provided with a plurality of replaceable cutting teeth 13. These teeth are arranged in pairs, one operative in one direction of rotation and the other in the opposite direction. For effective cutting action the angle of attack of the cutting edge of the operative tooth 13 relative to the tunnel face 14 (see FIG. 4) should be about 45. To prevent unnecessary and excessive wear upon the inoperative tooth it is held so that it is out of engagement with the tunnel face. Means is provided in accordance with the present invention to shift pairs of teeth so that one tooth of each pair is operative in one direction of rotation and the other in the opposite direction.

The structure shown in FIG. 1 is subject to considerable variation, in that different cutter wheel manufacturers employ different designs. As here illustrated, the central member 12 is octagonal, having on each side of its periphery a plate 16 from which extends a radial spoke structures 17, secured to plate 16 by gussets 18. Around the periphery of the cutter wheel is a rim 19 secured to the spoke structures 17 by reinforcements 21.

Spoke structures 17 may be substantially identical. As shown, each spoke structure 17 comprises a pair of spaced, parallel, longitudinal members 22 connected at their inner ends to plate 16 and at their outer ends to rim 19. Spaced outwardly and extending transversely between longitudinal members 22 are sets of three transverse members 23a, 23b, 23c. In a preferred form of the invention the spacing between transverse member 230 and the next adjacent member 23a is substantially greater than the distance between the members of each set, for a purpose which hereinafter appears. Members 23 are apertured along an axis which is radial relative to the axis of rotation of wheel 11 to receive a shaft 24, which is of a length equal to the distance between the outside edges of members 23:: and 230 of each set. A pair of tooth holders 26!, 261- is provided, holder 261 being positioned between members 23a and 23b, and holder 261' being positioned between members 2312 and 230. Each holder has a hub 27 which pivots about shaft 24 and spacers 28 are located between the edges of hub 27 and the adjacent members 23 to center the holder relative to the space between members 23. Extending radially from hub 27 is an arm 29, having at its outer end a tooth holding means 31. Each holding means 31 receives a tooth 13, and for such purpose c0- operating means are formed on-the tooth and holder. Such cooperating means are subject to wide variation, but as shown herein the means resembles that shown in Patent No. 2,968,880. In essence in the illustrated form of tooth and holding means, tooth 13 is formed at its proximal end with a slot extending forwardly and dividing said proximal end into a pair of rectangular cross-section prongs. Holding means 31 is formed with top and bottom flanges 32, 33, which fit on top of and beneath the prongs and the flanges are interconnected by a web (not shown) which substantially fills the slot. A resilient retainer fits between the web and prongs and resiliently-frictionally restrains unintentional withdrawal of the tooth from its holder. However, when it is necessary to remove the tooth for sharpening or replacement, it can be driven out of its socket against the resistance of said retainer.

Holders 26l, 26r are so formed and directed that the tooth 13 held by each is operative only in one direction of rotation. The back of each holding means 31 is formed with a flat face 34, which in the operative position of the tooth-holder engages pad 36 on one of longitudinal members 22, and when flat 34 is in contact with pad 36, as best shown in FIG. 4, the operative tooth 131 is held at an angle of attack of approximately 45 with respect to tun nel face 14 in the counter-clockwise direction of rotation of the cutter wheel. Hence as the machine is forced upwardly, as viewed in FIG. 4, and the wheel is turned in a counter-clockwise direction, the cutting edge of operative tooth 13l digs into the tunnel face and performs the cutting action. Between pairs of members 23a, 23b, 230 are pins 37 which engage the edges of arms 29 and limit movement of the inoperative holder 261' in the opposite direction. Thus as viewed in FIG. 4, the right-hand tooth 13r is located in inoperative position and its pivotal movement in a clockwise direction is restrained by one of the pins 37 shown in dotted lines. As thus held, the right-hand tooth 131- shown in FIG. 4 does not interfere with the cutting action of the left-hand or operative tooth 131, and at the same time the cutting action of the operative tooh does not dull or in any way damage the inoperative tooth.

So long as the parts are in the positions shown in FIG. 4, and the cutting wheel is turning in a counter-clockwise direction, the operative or left-hand tooth 13l will remain in its operative position. Upon reversal of the direction of rotation of the wheel, so that wheel 11 rotates clockwise, the left-hand tooth 13! will be turned in a counter-clock wise direction relative to wheel 11 by dragging across the tunnel face and against the debris cut by the cutter wheel until it reaches its inoperative position. A feature of the invention is the means whereby the right-hand tooth 131-, shown in FIG. 4, is pivoted into operative position when the tunnel machine begins to turn in a clockwise direction. A preferred means for such pivoting is a resilient member 41. In the form of member 41 illustrated, there is a central coil 42 having an inner tail 43 which is received in a hole in outer flange 32 and held in place by set screw 46. Note, as best shown in FIG. 3, that coils 42 of of the two holders of each pair are oppositely wound. Projecting out from the coil 42 in the opposite direction is a pigtail 44 whichprojects out farther than tooth 13 so that it engages tunnel face 14 and is bent backwards. When the direction of rotation of the wheel 11 is reversed, the outer end of pigtail 44 drags across the tunnel face 14 and hence retards holder 26r relative to wheel 11 so that it pivots counter-clockwise and brings right-hand tooth 13r into operative position.

In operation, one of the tooth-holders 26 and tooth 13 is initially in operative position and the opposite holder and tooth in inoperative position. Assuming that at the start the teeth are as shown in FIG. 1, the wheel 11 is rotated in a counter-clockwise direction and advanced toward the viewer. One set of teeth, i.e., the left-hand teeth 131 as shown in FIG. 4, excavate tunnel face 14, while the inoperative set of teeth 13) are in the position shown at the right-hand side of FIG. 4, with holder 26) engaging in the right-hand pin 37. The pigtails 44 engage the face 14 and are bent backwardly, the coils 42 facilitating the flexure of the pigtails. After a time interval, the wheel 11 is reversed in direction of rotation. Thereupon the lefthand tooth 13! pivots counter-clockwise around shaft 24 until the left-hand edge of its arm 29 contacts the lefthand pin 37. Meanwhile the pigtail 44 of the right-hand tooth 13;- digs into the face 14 and swings the tooth 13r upwardly in a counter-clockwise direction relative to the wheel 11 until its cutting edge engages the tunnel face 14, whereupon digging action commences. Alternation of the direction of the rotation continues.

When it is necessary to replace the tooth because it is worn, the wheel 11 is backed off from the tunnel face and the workman drives the tooth 13 out of its holding means 31, reversing the tooth, sharpening the tooth, or replacing it as conditions necessitate. When the springs 41 require replacement, the set screws 46 are loosened and a new spring 41 installed. If it is necessary to replace one of the tooth-holders 26, the shaft 24 is shifted along its longitudinal axis in a direction away from the particular tooth-holder to be removed. Since the space between sets of arms 23 is greater than the space between the arms in the individual sets, shaft 24 may be moved a sufficient distance to clear the hub 27 of the holder to be removed, whereupon the holder can be pulled out of the space between arms 23 and a new holder installed, whereupon the shaft 24 is moved back into position. If both holders 26 are to be removed, shaft 24 can be slipped first in one direction to remove the first holder and then in the opposite direction to remove the second holder.

What is claimed is:

1. A tooth structure for a pair of tunneling wheel teeth, one tooth of said pair operable when said wheel is turned in one direction and the other said tooth operable when said wheel is turned in the opposite direction, said structure comprising a first and a second tooth holder each formed with means to detachably hold a tooth, said holders oppositely directed relative to the directions of rotation of said wheel, support means and means pivotally mounting said holders on said support means for movement between operative and inoperative digging positions.

2. A structure according to claim 1 in which said lastnamed means comprises a shaft disposed parallel to the plane of digging action.

3. A structure according to claim 1 which further comprises for each said holder a resilient, outward-projecting finger adapted to engage the face of the hole being bored by said wheel and, upon reversal of direction of rotation, to dig into said face to retard rotation of said holder relative to said wheel and pivot the holder previously in inoperative position into operative position.

4. The structure of claim 3 in which said finger comprises a coil of spring wire and two projecting ends, one said end fixed to said holder and the other said end projecting outward relative to said holder.

5. In a tunneling machine wheel, a hub, a plurality of spoke structures radiating from said hub, and on each said spoke structure a plurality of tooth holders, each adapted to detachably hold a tooth, and mounting means for pivotally mounting said holders for movement about an axis transverse to said spoke structure between operative and inoperative digging positions, some of said holders di rected in one operative direction and the other said holders directed in the opposite operative direction relative to the direction of rotation of said wheel.

6. A wheel according to claim 5 which further comprises a resilient, outward-projecting finger on at least some of said holders adapted to engage the face of the hole being bored by said wheel and, upon reversal of direction of rotation, to dig into said face to retard rotation of said holder relative to said spoke structure and pivot the holder previously in inoperative position into operative position.

7. A wheel according to claim 5 in which said mounting means comprises a plurality of sets of members disposed transverse to said spoke structure and a shaft journalled in said members parallel to said spoke structure, said holders mounted on said shaft.

5 6 8. A Wheel according to claim 7 in which each said set References Cited mounts a pair of oppositely-directed holders on a single UNITED STATES PATENTS shaft.

9. A Wheel according to claim 8 in which the distance 2, 5,756 7/1937 Joy 29983 between adjacent sets is greater than the distance between 5 2, 10/ 1954 M h mp f a1 -91 adjacent members, whereby said shaft may be moved 3,301,600 1/1967 Pirrie et al. 299-56 along its axis in one direction to free the holder at the opposite end of said shaft for removal from said mounting ERNEST R. PURSER, Primary Examiner. means.

10. A Wheel according to claim 5 which further com- 10 U.S. Cl. X.R. prises means on said mounting means limiting pivotal 175-383, 85, 90 movement of said holders in either direction. 

